Cash acme BFP Backflow Preventer Questions

Docfletcher

What is the purpose of the vent on this BFP? What would cause it to weep water? This one is brand new, installed in October this year.

It only seems to weep after a week or so if I leave the street feed ball valve closed. I know I could just leave it open but I'm waiting to see if I'm losing pressure. Of course when it weeps I do lose pressure.

billtwocase

Ah, the cash cow of plumbing fixtures for the manufactures. If you get lucky, the vent will seat again. It is designed to open so a negative pressure on the street side won't collapse water heaters, etc. Although it is a check valve also, it must have the open vent. Just a suggestion, when my customers turn off their mains, I tell them to not relieve the pressure form the plumbing. As in run the faucet until it stops, of flush a toilet, etc. The pressure will help keep the vent side sealed with pressure left on the main

Docfletcher

Not sure I understand. When the street fill is closed the boiler is completely isolated from any street pressures. There is no way to relieve pressure from any plumbing fixtures in the house, as they all work normal.

By street fill ball valve I mean the valve that precedes the BFP. After the BFP is the automatic boiler fill valve valve (13PSI)

So when the vent weeps it is venting boiler water. At least i think it's boiler water because the boiler lost pressure when the vent was leaking.

hot_rod

Three seals need to be "made" inside the BFP. First the pressure needs to move a spool against a seal. This closes off the drain port and allows water to flow thru the two checks.

Most often, on first start, something gets in that first seal. Teflon tape, dirt, solder balls, and misc crud. If it leaks out the vent from day one, you can usually disassemble them and clean that seat.

See the spool and it's seal on the very left of the pic.

Different brands have different minimum pressure requirements to make that spool seal, make sure you have, and keep enough pressure on the valve to seal.

If they spit from time to time, that can be caused by water hammer aka elastic shock. The pressure spikes, then droops for an instant before going static again. This can cause that spool to back off it's seat for an instant.

Any fast acting valve, especially in a system that has high pressure can cause the occasional spit.

Wash machine solenoids, outdoor lawn sprinkler solenoids, even flushometers on toilets and urinals can cause the hammer that may cause a BFP to spit..

Water hammer arrestors back at the cause can help eliminate that spike induced spitting. Some plumbers tell me an additional swing check upstream will take the hammer and keep the BFP from spitting?

Here are the cut aways I use in training, for pass arounds. It shows the various seals and how easily they can be dis-assembled, checked and cleaned. Most are assembled with fine threads and o-ring seals. A small channel locks will break them apart.

I would say this is the most often returned valve in all of hydronics If you have tried all the various brands and still have leak issues, it's not the valve!

Or the valve is doing what it was intended to do.

Don't bother plugging the vent port, the label rivet holes are drilled into the vent chamber

It's good practice to put a pipe or pex into the vent port and take it to the floor, or near a floor drain. They tend to spit or spray on the most expensive components in the mechanical room.

Docfletcher

Gezz, when the old one started to leak Sept of 2013 I plugged it. For some reason it did not leak through the rivets, lucky I guess.
In October this year I replaced it thinking maybe it's bad.

I agree with you that pressure needs to be applied to the valve to seal. That's why it don't leak when the street fill valve is open.

The auto feeder may be bad, it has a built in check valve and should not allow boiler water to go back out to the BFP.

My setup is pretty much as shown her...

http://screencast.com/t/Y4n0jtPJYK

hot_rod

The only value of the check in the fill valve is it allows you to disassemble and repair that valve without draining down, IF it holds. Before BFPs were mandated that was the only protection.

Now in some areas you can still use a double check BFP without that vent port, maybe some areas of NY? That solves the leaking port issue.

Also it depends on what is in the system for fluid, the hazard level. When I did fire protection the code was very specific on the type of BFP and they were required to be certified yearly. I doubt many residential hydronic systems have a yearly BFP check.

Most public water system connections are required to have BFPs. Something to do with the CWA and getting access to federal and state funding.

You may find the BFP built into meter yokes provided by the utility or other parts of the piping, most HO don't even know they have a BFP. Until the water heater relief valve starts seeping.

I don't know for sure if the label holes are drilled on that brand, they are on the Caleffi.

If you have a plug in the vent, you no longer have an approved functioning BFP. Just an expensive brass nipple

Some of the manufacturers are now inserting a small screen at the BFP inlet connection. If you have slow fill rate, good chance the small, fine screen is plugged.

billtwocase

misunderstood you when you said water main. You also do not want to plug off the vent. Is there a shut off after the auto feed on the boiler side? If you keep the auto feed valve off, I prefer closing the valve on the boiler side, and leaving the BF under street pressure at all times. I will help to keep it sealed. This is only if 2 shut offs were installed.

icesailor

Al lot of quality installers use two valves on the BFD and PR Fill Valve. One AFTER the fill valve. So that if you ever have to replace either or both the BFD/PRV, you don't have to drain the boiler.

If you leave both or just the one between the PRV closed, you don't have differing pressures on the BFD.

As far as I know, most PRV/Boiler fill valves have a rubber ball check inside the PR valve. If the first feed valve is closed, and the BFD valve is leaking, either the BF valve is installed between the fill valve and the boiler, where it isn't supposed to be, or the check ball is dirty and failed. Back a few years ago, it seemed to have become a Urban Legend that the BFD went AFTER the fill valve. It became such a problem that most manufacturers like Watts came out with their "9-11" Combination backflow and fill valve. To stop the improper and illegal installation of their valve. Defeating the purpose. I believe that Califfi sells the same type. combination valve.

billtwocase

I had the best results with Conbraco products. Problem is finding suppliers of their products. Kind of like the Beacon 69's. They are just there for decades doing their job. Watts products have improved, but still have some issues.

icesailor

Beacon was a product of the Chinese Knock-off-s and being unable to stop it. Then, when they were in Bankruptcy, a large US manufacturer bought them out because if the proprietary, patented products that owned, and they had them manufactured in China, to be sold by we good Americans to help the downfall of manufacturing jobs in the USA.

Beacon "610 Toilet Anti Sweat Valve". is now the exact same valve with another manufacturer's name stamped into it.

Docfletcher

Biltwocase, yeah I kinda thought you misunderstood. In retrospect I think I could have been a little clearer imparting what I was saying.

So I don't have a 2nd ball valve after the auto filler. A thought for the future perhaps.

Right now the vent is plugged and the BFP is not weeping The ball valve before the BFP is closed, and boiler pressure seems correct. When I'm satisfied no leaks in the system I'll open the ball valve and pull the plug. Photos of the old BFP, which is probably still good.

http://screencast.com/t/iCuBdyIUc

http://screencast.com/t/E3Nr2gyZU

http://screencast.com/t/fhGzhEnjIw1l

icesailor

If that arrow on the Fill Valve is pointing at the BFD, it is installed wrong and backwards. For that rust scale to be on the seat of the BFD as shown in the other photo's, it had to be in direct contact with the boiler water. When installed correctly, there is absolutely no boiler water that can come in contact with the BFD, unless the check ball in the PRV is leaking by and defective.

If the BFD is connected directly to the heating system, it is installed improperly. If the BFD is installed correctly, only Potable water will be in contact with the inlet and outlet end of the valve.

Enlarge this link. Notice that the BFD says "Inlet" on one end, it is direct connected to the PRV, which has a flow arrow clearly embossed on the side of the valve, pointing to the direction of the flow.

http://www.watts.com/pages/_products_details.asp?pid=669

The ONLY way you can separate the two parts and use them improperly is to have a very large hex head male socket and remove the end of the union where it goes in to the PRV. Unless you have an old valve, it is difficult to swap them around. The problem was so bad that they made this 9-11 valve to stop unsafe installations.

Docfletcher

The arrow is pointed at the fill valve. I suspect the check ball is leaking, allowing boiler water to enter the BFP and weep out through the vent. I suspected it actually last year when weeping gave me cause to plug the weeping vent.

I can't replace the fill valve at this time though. This boiler has suffered from lots of make up water. I don't want to draw it down then add more water to it.

I think it's fouled with iron oxide inside, that's why it has trouble sensing temperature accurately. IE: High limit set 165 but actually flame off at the correct 180F.

icesailor

That problem is usually the sign of a failing control. If there's room, put a 1/2: Ball Valve between the boiler and the valve. Leave it off, and your problems go away. If it connects to a copper adapter on the return/supply line on the boiler, and they used a steel nipple between the adapter and the bronze valve, it will rot and corrode the nipple. Use a brass nipple. You won't have that problem.

Docfletcher

Well, back in the fall of 2012 the culmination of several component failures was the PRV spewed water all over the place. The limit control failed as well as witnessed by the pressure gauge's high pressure reading and temperature reading. I don't remember the exact temp, but it was something ridiculous like 260F. That's when I put in the new limit control. Which as I previously explained seems to be inaccurate. To prove it out I would need purchase another at $100 plus. I am reluctant to do so.

Currently there is no room for a ball valve after the fill valve which does have have its connections to the boiler with black iron... But, the fill valve is cast iron itself.

http://screencast.com/t/apY1KZ6ChmX

http://screencast.com/t/acptHmGS

Docfletcher

Someone from I can't remember where thought a thermal conductive grease should be used on the limit probe that goes into the the well in the boiler. Not sure about that so I have not tried it. I mean, why dink around with it. It's shutting down and starting again right where I need it to.

billtwocase

I wouldn't use that conductive in the well. When you replace the control, and sounds like it needs to be, the probe will be glued in there. No fun, and that stuff should never be needed. Always make sure the probe bottoms out inside the well.

Docfletcher

Yeah, I heard that also about the thermal grease. The Honeywell limit control that came with the boiler was bolted to the side cover wall, the bulb which mounts in the well was tethered to the limit control with 10" of solid copper wire. So with that limit control you might have a little more leeway in bottoming it out.

On the new style Honeywell limit control the bulb is not tethered. The bulb simply protrudes out of the limit control body and the unit is inserted as whole, secured with a one screw locking collar.
You can get the end of the bulb to bottom out but there is not enough slop so you can get the whole length of the bulb bottomed.
When I put the new limit in I also replaced the well. So if I were to use thermal grease and it got hard and another limit control was needed I think I could cut cut the bulb, remove the limit then the well & replace the whole thing again.